[turbofan] Tester improvements; use CSignature and simplify ReturnValueTraits.

test/cctest/compiler/test-simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits>
 
 #include "src/compiler/access-builder.h"
 #include "src/compiler/change-lowering.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/graph-reducer.h"
@@ skipping 15 matching lines @@
 #include "test/cctest/compiler/graph-builder-tester.h"
 #include "test/cctest/compiler/value-helper.h"
 
 using namespace v8::internal;
 using namespace v8::internal::compiler;
 
 template <typename ReturnType>
 class SimplifiedLoweringTester : public GraphBuilderTester<ReturnType> {
  public:
   SimplifiedLoweringTester(MachineType p0 = kMachNone,
-                           MachineType p1 = kMachNone,
-                           MachineType p2 = kMachNone,
-                           MachineType p3 = kMachNone,
-                           MachineType p4 = kMachNone)
-      : GraphBuilderTester<ReturnType>(p0, p1, p2, p3, p4),
+                           MachineType p1 = kMachNone)
+      : GraphBuilderTester<ReturnType>(p0, p1),
         typer(this->isolate(), this->graph(), MaybeHandle<Context>()),
         javascript(this->zone()),
         jsgraph(this->isolate(), this->graph(), this->common(), &javascript,
                 this->machine()),
         source_positions(jsgraph.graph()),
         lowering(&jsgraph, this->zone(), &source_positions) {}
 
   Typer typer;
   JSOperatorBuilder javascript;
   JSGraph jsgraph;
@@ skipping 2039 matching lines @@
     Bounds phi_bounds = Bounds::Either(Bounds(d.arg1), Bounds(d.arg2), z);
     NodeProperties::SetBounds(phi, phi_bounds);
 
     Node* use = t.Use(phi, d.use);
     t.Return(use);
     t.Lower();
 
     CHECK_EQ(d.expected, OpParameter<MachineType>(phi));
   }
 }